Machine for sharpening circular saws, milling-cutters, and the like



Oct. 29, 1946.

C. E. DRAKE MACHINE FOR SHARPENING CIRCULAR SAWS, MILLING-CUTTERS, AND THE LIKE Filed Aug. 2, 1943 4 Sheets-Shet 1 Oct. 29, 1946. Q DRAKE 2,410,274

MACHINE FOR SHARPENING CIRCULAR SAWS,

MILLING-CUTTERS, AND THE LIKE 1 Filed 'Aug. 2, 1943 4 Sheets-Sheet 2 z 'Z ML,L

C. E. DRAKE MACHINE FOR SHARPENING CIRCULAR SAWS,

MILLING-CUTTERS, AND THE LIKE Filed Aug. 2.; 1943 Oct. 29, 19.46. 7 2,410,274

4 Sheets-Sheet 3 c. E. DRAKE 2,410,274 MACHINE FOR SHARPENING CIRCULAR SAWS,

MILLING-CUTTERS, AND THE LIKE Filed Aug. 2. 1943 4 Sheets-Sheet 4 Patented Oct. 29, 1946 UNITED STATES PATENT" OFFICE MACHINE FOR SHARPENING CIRCULAR SAWS, MILLING-CUTTERS, AND THE LIKE Claud E. Drake, Brentwood, Mo. Application August 2, 1943, Serial No. 496,995

6 Claims.

This invention relates to a certain new and ening in succession all the teeth or only every alternate tooth of a particular saw or cutter, which may be economically constructed, and

- which is elr'icient in the performance of its intended functions.

And with the above and other objects in view,

- A for arcwise shifting the grinding-wheel or rotary abrader a into and out of the gullets between the respective teeth of the saw, an arboras'sembly C readily vertically and horizontally adjustable relatively to the abrader a, indexing mechanism D for efiecting rotary actuation of the arbor and supported saw in timed relation with reciprocations of the abrader a, means, generally indicated E, for effecting horizontal or traversing reciprocation of the grinding wheel a relatively to the particular saw being sharpened, and a train of gearing F and a motor M for actuating allof the moving or movable parts of the machine, with the exception of the abrasivewheel a, in timed or synchronous relation.

All the parts or components of the machine are mounted directly or indirectly on, and supported my invention resides in the novel features of form,

construction, arrangement, and combination of parts presently described and pointed out in the claims. Y

In the accompanying drawings (four sheets)- Figure 1 is a front elevational view of a sawsharpening machine embodying my invention;

Figure 2 is an elevational view of the righthand side of the machine; I

Figure 3 is an elevational view of the opposite or left-hand sideof the machine;

Figure 4 isa fragmentary broken view of the machine similar to Figure 1, illustrating parts of the machine in altered or adjusted positions;

Figures 5 and 6 are enlarged sectional plan views of the machine taken approximately on the lines 5--5 and 6-45, respectively, Figure 1;

Figure 7 is a vertical sectional view of the machine taken approximately on the line 11, Figure 2;

Figures 8 and 9 are similar views taken approximately on the lines 88 and 99, respectively, Figure 7; and

Figure 10 is a diagrammatic view illustrating several of the tooth grinding or sharpening operations that may be selectively performed by the machine.

Referring now more in detail and by reference characters to the drawings, which illustrate a practical embodiment of my invention, the machine includes a vertically and horizontally adjustable carriage assembly generally indicated A, forming part of which is a preferably independently motor-driven abrasive or grinding wheel a of a selected size and shape suitable for the sharpening of a particular disk-saw, cam-operated mechanism generally designated B forrockably or pivotally lowering and elevating the carriage by, a suitable upstanding preferably oblong-- rectangular casing or housing H comprising a base portion I, a front wall 2', joined to which by a lateral wall 2" is an offset continuation or extension 2",- a left side wall 3, a right side wall 4, a rear wall 5, and a top wall 6. It will be understood that the housing H, while, for illustrative purposes, here shown as an integral unit, is in practice constructed of suitable sections for convenient, facile assembly. I

As best seen in Figures 1, 2, and 5, the grindingwheel supporting-carriage A comprises a suitably located horizontally disposed shaft 1 fixed at its rear end in the rear housing-wall 5 and at its forward end in the front housing-wallcontinuation 2", andmounted on the shaft I for both rocking movement and endwise reciprocation from front to rear and from rear to front of the housing H, is a suitably elongated sleeve 8.

Suitably fixed at an end to and upon the forward end of the sleeve 8, and projecting outwardly through a suitable opening, as at 2*, in the housing-wall 2 to endwise extend crosswise of the front housing-wall 2, is an arm 9 suitably grooved upon its upper and lower faces, as at c, for dovetail-slidable connection with a frame l0.

Suitably mounted for rotation in bearings or bosses I l on the front face of arm 9 and suitably engaging the frame III, is a screw-shaft l2 equipped at an end with a manipulating handwheel I 3. I

In turn, having suitable sliding connection with, and disposed upon the front face of, the frame [I], is a block [4, and suitably mounted for rotation in the frame l0 and having threaded connection with the block I4, is a second threaded or screw-shaft l5 also equipped at its upper end with a manipulating hand-wheel l6.

Suitably supported on, and shiftable relatively to the housing H with, the block it, is a suitable small prime-mover or motor i1.

Suitably journaled in the block i4, is a small shaft it, to and upon which the selected abrasive or grinding-wheel or abrader a is detaohably secured, shaft 18 being driven at a constant predetermined or selected speed through a suit! able belt and-pulley connection l3 with the mtor i'i.

It will be evident that, as shaft i2 is rotarily actuated through the hand-wheel I3, the block 14 and its associated abrasive-wheel a will be adjustably shifted laterally or horizontally with respect to the housing H and thereby positioned at a selected distance or location relatively'to the axis-shaft for tooth radius grinding, aspresently more fully appears, and that as shaft i5 is rotarily actuated through th hand-wheel it, the block [4 and associated abrasive-wheel a and-motor ill will be adjustably or selectively raised or lowered or shifted vertically with re spect to the housing H, for purposes shortly appearing. It may be observed here that thus a wide range of settings or adjustments of the abrasive or grinding disk a may be quite readily effected.

As best seen in Figure 7, the motor M is suspended from the housing top-wall 6 and by means of a belt and pulley drive I9 and the train of interposed speed-reducing gearing F actuates at the proper and desired peed for most efficient operation a main drive-shaft 26 journaled, as best seen in Figures 5 and 9, in suitable bearings 2i mounted on and projecting inwardly from v housing-wall 4.

Fixed on shaft 20 from left to right, as viewed in Figure 9, are the final gear 1 of the speed reduction train F and also for purposes presently appearing, a bevel gear 22, spaced collars 23 and 24, a gear 25, and a suitably shaped cam 26, a so-called skip-tooth cam 2'? preferably integral with a gear 28 being loosely sleeved and retained on the shaft 28 intermediate the collars 23 and 24. M

It may be observed here that, when desirable, a change in speed may be effected byany suitable means, such as, for instance, the transfer of the belt from the full line to the broken line position, as shown in Figure '7, as will be understood, and it should be noted that the gearing F is merely illustrative of any suitable speed reduction train, a description of which in detail is here omitted.

Synchronism of the moving parts of the machine being essential for successful operation, preferably a single prime-mover M is employed to actuate all of such parts except the abrasivewheel a, which latter may rotate at a suitable speed independently, as will be understood, the rockable actuations of carriage A and reciprocations of the traversing mechanism E, in synchronization with the indexing apparatus D, being thus effected from the motor M as the single source of power.

As best seen in Figures 5, '7, and 9, the tubular shaft or sleeve 8 is preferably integrally formed with a laterally extending relatively wide arm 8 having a smooth flat under face, as at (Z, and at its face (I rests, and is reciprocable both lengthwise and crosswise, upon a roller 29 journaled for rotation upon a pair of suitably spaced angular brackets 30 mounted for slidable adjustment in a way provided in'the upper face of an arm e of a bell-crank lever 3| pivotally mounted, as at 32, upona bracket 32 fixed upon the housing-wall 4, as shown in Figure '7. Engaging a 4 boss or enlargement is in the lever-arm e and having connection with the brackets 30, is a screw-shaft 33 having a manipulating handwheel 3% for selectively shifting the brackets 30 and roller 29 as a unit for positioning the roller 29 either toward or away from the stationary pivot shaft 1 for purposes presently appearing, the other or upstanding arm h of thecam-lever 3! and the housing-wall 4 being apertured in registration, as at, 32 for accommodating the screw-shaft 33.

As best seen in Figures 5 and 9, the cam-lever Si is formed preferably integrally with a rightangular lateral extension 3%, which, under the weight of arm 8', is in constant engagement with cam 26, as will be readily understood. It follows then that, as the rotary drive shaft 20, in operation, rotates the suitably shaped cam 26, the arm 8 and consequently thesleeve 8 and arm 9 and simultaneously the abrasive wheel a will be alternately rocked and thereby angularly or arcwise lowered into and raised out of the gullets g of successive peripheral teeth t on the saw S being ground or sharpened.

Obviously, the external configuration or shape of the cam 26 is important and must be precisely designed to meet different requirements in toothgullet depths and to insure adequate elevation of the abrasive-wheel a to allow intermittent indexing without burning the points of the'teeth of the particular cutter or disk S being sharpened. In other words, the cam 26 is so designed that the abrasive-wheel a is slightly raised or elevated above the peripheral extremity of each tooth and maintained in that position until the indexing mechanism D brings the succeeding or following tooth into grinding position. Obviously, however, by varying the contour of the cam 26, the wheel a may be so rocked relatively to the rotary movement of the saw S being sharpened as to engage the successive teeth 1? thereof for grinding a gullet and back wall of desired curvature, as well asalso a so-called land thereon for purposes well understood. Each machine will, in practice, comprise any desired number of differ ently or selectively contoured cams 26, which are readily interchangeable on the drive shaft 28 to meet the requirements of any particular saw user.

It may be here remarked that, when it is desired to sharpen alternate teeth of the saw, the cam 2? and a suitable speed reduction gear train are brought into operation. As best seen in Figures 5, 7, and 9, the lever-arm lit at its upper extremity is bifurcated to provide a suitable recess in which is pivotally mounted, as at 34, an auxiliary cam-plate 35 comprising a vertically extending portion or leg 35' and a laterally and downwardly extending portion 35"., Threadedly engaging the latter and located directly over the screw 33 and presented at an end outwardly through a suitable opening 36 in housing-wall 4, is a short horizontal screw-shaft 31 provided with a manipulating hand-wheel 31*, as shown.

Screw-shaft 31 passes threadedly through the leg 35 of the auxiliary cam-plate 35 and, when rotarily actuated in one direction, will at its inner extremity impinge upon the presented face of the lever-arm h and at the same time will tilt the leg 35' to engage the skip-tooth cam 21. Conversely, upon opposite rotation of the screwshaft 31, its extremity will be withdrawn from engagement with the: lever-arm h and at the same time leg 35" will be swung out of engagement with the fskip-tooth cam 21. The latter setting is had when each succeeding tooth of the particular cutter S is to be sharpened; the former is had when only every other tooth of the particular cutter S is to be sharpened or ground.

It should here be noted that, whenever the skip-tooth setting is had, cam-plates 3i and 35 function as a unit with respect to cam 21, so that any movement imparted to the auxiliary cam-plate 35 will be likewise imparted to the primary cam-plate 3| which latter, as previously mentioned, controls the up-and-down or rockable reciprocations of the grinding-wheel a.

As also previously stated, the skip-tooth cam 2-! is loose or sleeved on the main drive shaft 25 and hence is freely rotatable thereon. Said cam 21, however, must rotate at precisely one-half the speed of rotation of the main drive shaft 20, as will be understood, and this exact reduction is obtained by means of a gear train which includes the gear 28, a gear 38-of reduced diameter meshing therewith, and a gear 39 of a larger diameter in mesh with the smaller diametered gear 25 fixed on the main shaft 29. Gears 38 and 39 are rigidly fixed and supported on a relatively short shaft 45 journaled in bearings 4| projecting from housing-wall 4, as best seen in Figures '7 and 9.

The particular peripheral shape of cam 26 is such as to meet the requirements for sharpening an unlimited number of cutters having similar teeth, and consequently cams of modified shape may, as has been stated, be substituted to meet the requirements for sharpening cutters or disksaws having teeth likewise modified, as will be understood. The peripheral shape of cam 21, however, is such, it may be mentioned, that its high point or lobe 27 is farther removed from the axis of shaft 25 than is the highest point of the lobe which may be formed on any one of the cams 26 selectively employed for a particular type of saw.

In the event that a number or plurality of circular saws are to be tooth generated or tooth sharpened at one and the same time or in the event that a milling-cutter of substantial width or thickness is to be tooth generated or sharpened, then it becomes necessary that the rotary grinding-wheel be caused to also travel transversely of the particular saws or cutter. The means E, best seen in Figures 1, 3, 5, and 7, for such purpose, that is, for reciprocating the abrasive or grinding-wheel a transversely across the face of the teeth of the particular cutter will now be described. Driven by the motor M, as by a belt and pulley assembly 42, is a shaft 43 mounted in suitable bearings 44 located on the top housing-wall 6 and suitably extended to support adjacent housing-wall 3 a fixed variable pulley 45 co-operable by means of a belt 45 with a similar pulley 4'! on a stub-shaft 41' suitably j ournaled on housing H, whereby changes in the driven speed of the latter may be had by shifting belt 46, as well understood.

Integral with or suitably secured to the variable pulley member 41, is a suitable disk 48 provided with a series of spaced threadedly apertured or recessed bosses 49, each occupying a different position radially outwardly from the axis of the disk 48. Engaging a suitable screw or the like 50 projecting through a journal-member 5| of aconnecting-strap or reciprocating rod 52 with any selected one of such bosses 49 will effect a variation in the reciprocal travel or stroke of such rod and consequently also of the grinding-wheel a, as will now be apparent.

The connecting rod or strap 52 has a pivot connection, as at 53, with the outer reduced end ofan oscillatory horizontally disposed member 54 having a shape or contour best seen in Figure 7. Such member 54 is yoked at its inner end for piVot-pimconnection, as at 55, with a bearing bracket 56, in turn, secured to and projecting from housing-wall 5, said'member 54 at its outer end-portion projecting outwardly of the housing H through a suitable opening 57 formed forthe purpose in the housing-Wall 3.

Approximately centrally, the member 54 is provided with an opening, as at 54, which, as best seen in Figure 7, not only accommodates the elongated sleeve 8 reciprocable on shaft 1', but

also a ring 58 welded or otherwise secured to the sleeve 8, and projecting from the ring 58 and loosely seated in slots 59 in the opposite side bars 54 of oscillatory member 54, is a pair of preferably integral diametrically opposed pins 60 for imparting endwise movement to the tubular-shaft 8 on rockable actuations of the member 54.

The structure C for mounting and positioning the disc-saw or cutter supporting arbor in proper spaced relationship with the abrasive wheel a will now be described. As best seen in Figures 1, 4, 6, and 7, 6| designates an angularly shaped arbor supporting member, which comprises a horizontal or table portion 6| and a depending or leg portion 6 l At its portion 61f the member 6! is preferably integrally formed upon its upper face with a boss or enlargement 6| providing a bearing for the smooth portion of a relatively long screw-shaft 62, which projects at one end outwardly of the housing H through an elongated slot 63 in housing-wall 4 and has fixed thereon a suitable manipulating hand-wheel 64.

At its portion 6i, the member BI is mounted for vertical sliding movement in a dovetail-slideway formed by a pair of suitably spaced cooperating strips secured to housing-wall 4 as by screws 66 or the like.

The desired elevation of support BI is readily ob-tainableby rotation of a handwheel 61 rigid on the outwardl projecting end of a short shaft 68 journaled in a bearing in housing-wall 4, as best seen in Figure 4. Fixed to and upon the other or inner end of shaft 68, is a bevel-gear 69, which is in mesh with a similar gear 19 fixed to and upon the upper end of a vertically disposed screw H, which passes threadedly through a depending boss 61 of the support 6! and which, at its lower extremity H, is rotatably supported in a bearing block 12 projecting inwardly from, and bolted or otherwise secured to, housing- Wa1l4,

The horizontally disposed portion iii of support 5i is given added strength and rigidity by one or more integral webs or braces 6!, as shown, and is provided along the greater portion of its lateral margins with suitable ways Si for supporting a slidable base or platform 13, upon the upper face of which are suitably fixed bearings 14, 14, for the arbor or cutter-supporting shaft 0. As best seen in Figure '7, the elongated screwshaft 52 has threaded connection with platform l3, and hence lateral movement of the platform F3 in either direction may be conveniently effected b rotation of hand-wheel 64.

The indexing apparatus D forms the subjectmatter of, and is illustrated and described fully and in detail in my co-pending application, Serial No. 492,558. Hence a detail description thereof is here omitted, reference in that regard being made to my said'copending application Suffice now to say that such apparatus intermittently rotarily shifts the particular saw or cutter being sharpened in one direction through arcs of precise predetermined extent. Such mechanism is supported in spaced bearing brackets '15 depending from the shiftable platform 13 and is driven by bevel gearing, as at 16, in turn driven by the main shaft 29 through meshing engagement between bevel gearing TI and gear 22, the gear 16 having meshing connection with a gear 18 having shiftable key-connection, as at 19, with a vertically disposed driven shaft 80 journaled in suitable bearing brackets 81 and longitudinally slotted, as at 89, for the purpose.

A suitable opening 82 is formed in the front housing-wall 2 through which the arbor C projects, and the latter is provided with any suitable means, such as indicated at 83, for selectively and removably mounting thereon the peripherally toothed cutters r saws S to be sharpened.

Before now describing the full operation of the machine, it is to be noted that the pulley 41, when the grinding-wheel a is to be caused to traverse the particular cutter or saws being sharpened, is freely rotatable on the stub-shaft 41, However, normally, as it may be said, or when merely a single saw S is being tooth sharpened or tooth generated, traversing action of the grinding-wheel a is omitted, as has been previously stated, In such event, the pulley 41 is fixed, as by means of a thumb-screw or the like 41" engaged with the shaft 41' and either belt 42 disengaged from shaft 43 or belt 46 disengaged from pulley ll and thus, in turn, through the rigid link connection 52 and slot-and-pin connection 59, 60, the tubular-shaft 8 and its associated parts are retained or secured from endwise reciprocation on the fixed shaft 1.

In use and operation, let it be assumed that a circular or disk-saw S, indicated in dash lines in Figure 1 and diagrammatically and fragmentally in full lines in Figure 10, is to be sharpened and that the cutting faces of its respective teeth t are not only of hook form, but are additionally arcuately formed, as at t, from their gullets g to their points p.

Such saw S being properly mounted on the arbor C, the precise degree of so-called hook and the desired arcuate radius thereof having been mathematically or otherwise accurately predetermined, and tube or shaft 8 being retained, as has been described, from endwise reciprocation on shaft 1, traversing action of the grinding wheel a being unnecessary, the screw-shafts 62 and T8 are first rotarily actuated by means of suitable turning movements imparted thereto by their respective hand-wheels 64 and B1 and the arbor C and supported cutter S thereby shifted vertically and horizontally with respect to the housing H for accurate peripheral engaging relation with the abrading-wheel 11. Thus the machine may accommodate saws or cutters of a wide diametrical range and the arbor C conveniently positioned relatively to the grinder a for obtaining the desired hook.

Then, through suitable rotary manipulations of the hand-wheels l3 and IE5, the grinding-wheel a may be further vertically and horizontally adjustably shifted with respect to the pivot-shaft 7 for obtaining the proper degree of radius cutting in the teeth t of the particular saw S, or, in other words, by shifting the wheel 0 toward or from the axial line of the shaft 1, the degree of radius cutting by the grinder a in the teeth t will be greater or less as may be necessary to meet the requirements of any particular saw. And it will be understood that, since all of such adjustments are screw-controlled, precision and accuracy are readily, conveniently, and positively obtained.

Further, by suitable manipulation of the handwheel 33 the disk or roller 29 is selectively shifted outwardly or inwardly of the housing H and relatively to the under face (1 of the lever or arm 8' for thereby shifting the fulcrum with respect to the arm 8 for correspondingly varying the extent of rocking movement of the shaft or sleeve 8 on the shaft 1 for precisely gauging the rise and fall or arcwise reciprocations of the grinding-wheel a into and out of the teeth-gullets g, in co-operation with the intermittent timed indexing action of the mechanism D.

It follows that, as the drive shaft 2!] is caused to rotate, the cutter or saw S is rotatably actuated intermittently or step by step through and by the indexing mechanism D and, in timed 0r synchronous relation, the rotary grinding-wheel a, independently driven by the motor I1, is shifted arcwise downwardly into and out of the tooth gullet g, whereupon the cutter S is again rotarily actuated by the indexing mechanism D sufficiently to dispose a succeeding tooth into sharpening position.

However, if a plurality of saws or a cutter of some width or thickness are being sharpened at one and the same time, then, by disposing the thumb-screw or like member 59 in a selected threaded socket 39 of the pulley 48, the member 54 will be rocked on its pivot or fulcrum 55, and through the slot and pin connection 59-439, the rock-lever 8 will be shifted endwise on the shaft 1 and also on the roller 29 inwardly and outwardly with respect to the housing H, whereby the cross-arm 9 and its carried grinding-wheel a will correspondingly be caused to traverse the width or thickness of the particular saws or cutter S being sharpened, the amount of such traverse movement being varied by selectively locating the thumb-screw 59 in one or the other of the sockets G9, and the speed of such traversing movement being also selectively varied by shifting the belt '46 into one or the other of the cones il.

Under such circumstances, it like-wise follows that, as the drive shaft 29 is caused to rotate, the saw S is rotatably actuated intermittently or step by step through and by the indexing mechanism D, and in timed or synchronous relation, the rotary grinding-wheel a, independently driven by the motor I1, is shifted first arcwise downwardly into a tooth gullet g, then caused to traverse such gullet g, and then shifted outwardly of such gullet g, whereupon the cutter S is again rotarily actuated by the indexing mechanism D sufficiently to dispose a succeeding tooth i into sharpening position and the grinding-wheel a then caused to follow the same tooth sharpening paths, and so on throughout the entire periphery of the particular saw S. Thus any number of like saws may be quickly and efficiently sharpened without any further adjustment in any of the mechanism of the machine. I

In this connection, and having reference specifically to Figure 10, in which a: indicates the arcuate path of the abrasive-wheel a in a toothsharpening operation, it will be understood that, should the desired tooth curvature t be of small or acute radius, as at r, the carriage A with its grinding-wheel a are shifted toward the axis of the pivot or rock-shaft I, as shown in broken lines. If a more pronounced curvature Or a curvature of more obtuse radius, asat 1", is desired,

distance or relation to the axis of the shaft l.

, It will be seen that the machine is so flexible in providing for adjustments in locating the position of the arbor C, of the carriage A, and of the grinding-wheel a, as well as also in the extent of travel of the grinding-wheel a relatively to the particular cutters,- that the machine will readily accommodate, and efi'iciently and quickly effect sharpening of, cutters of various diameters and shapes or contour of teeth. For example in Figure 10, cutters or saws'of four different sizes are shown, with the arbor C andthe grinding- Wheel a selectively located'for obtaining the de- .siredtooth hook and radius. A smaller diam etered cutter S may be'sharpened as precisely and accurately as a larger diametered saw S Within the range of adjustments provided by the machine, the unlimited grinding scope inherent in the machine being evident from a comparison of the saws S and S or S and S. From such comparison, the wide'scope or range of saw tooth sharpening obtainable in the present machine is quite apparent.

It may also be observed that more than one saw or cutter suitably mounted in aligned r lation on the arbor C may be simultaneously sharpened, the particular grinding-wheel 1! ice-- ing properly sized and its traversing movement being gauged accordingly, and, as has been tioned, by manipulating the hand-wheel 37 rocking up-and-down and traversing movements of the brasive-wheel a may be lengthened with respect to the indexing travel of the particular saw S, so that merely alternate teeth of the particular saw S are sharpened during a full rotary cycle thereof.

It might also be mentioned that, by substituting difierently shaped cams 2%, the amount and relative speed of swinging movement of the abrasive-wheel a during an indexed or rotary movement of a particular saw may also be selectively varied for generating or sharpening teeth of different tooth contour, and that, by disengaging belt 46, the grinding-wheel a may be manually shifted in a traversing operation.

It may be added that the machine, while here more particularly described in connection with the sharpening of the teeth of the saw or cutter, may very efficiently be used and employed in initially generating teeth of selected contour and radius upon the periphery of a circular disk or cylindrical cutter-body.

The machine eifects the production of a toothform by a simplified mechanical action, truly automatic and not dependent upon the skill of the operator in coordinating various controls. Further, index plates are eliminated, a universal indexing apparatus especially designed for and built into the machine accurately indexing for any pitch on any diameter cutter or saw. The operator counts the teeth in the tool to be ground and sets the index accordingly. Also, pivoted side suspension of the grinding-Wheel assembly provides for the up and down movement of the grinding-wheel ona curve, the radius being easily adjusted. Obviously, this design brings radius grinding on the face of the tooth under positive control and uniformity, eliminating the need of wheel dressing to produce curved tooth face.

Tooth contour is formed on this machine in a practical manner. Reproduction of a given tooth shape is a matter of mechanical selection, eliminating the human element and guesswork.

Instead of varying the speed of each indexing stroke (allowing the wheel to dwellinthe gullet, then increasing the speed of indexing to flatten off the tooth point or land), the'machine em ploys a constant, unvarying rate of speed throughout the indexing stroke, the rate of speed of raising the grinding wheel a being slowed to grind the land. This movement is inherent in the grinding-wheel actuating cam, and hence requires no delicate co-ordination of wheel and index controls by the operator. This feature assures any desired tooth shape with overall uniiormity, and economizes in time in setup.

The machine simplifies the control of. the degree of land ground on the tooth. The operator merely selects the degree of land to be ground, and no prolonged, delicate timing or co-ordination of controls is required.

The machine fulfills in every respect the objects stated, and it is to be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the machine may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a machine for sharpening circular saws and the like, a rockable shaft, an arm fixed to and rockable with the shaft, an abrasive-wheel supported for rotation by the arm, an arbor for supporting the saw to be sharpened, means for r0- tarily actuating the arbor and supported saw, and means for rocking the shaft and arm for arcwise shifting the wheel into and out of engagement with the periphery of the saw, said last means including a second arm fixed on the shaft, a pivoted bell-crank lever having actuating connection with the second arm, and a rotary cam. having peripheral engagement with the bellcrank lever.

2. In a machine for sharpening circular saws and the like,a rockable shaft, an arm fixed to and rockable with the shaft, an abrasive-wheel supported for rotation by the arm, an arbor for supporting the saw to be sharpened, means for rotarily actuating the arbor and supported saw, and means for rocking the shaft and arm for arcwise shifting the wheel into and out of engagethe bell-crank lever.

3. In a machine for sharpening circular saws and the like, a rotary abrasive-wheel, an arbor for supporting the saw to be sharpened, and means for causing the wheel to reciprocate through selected distances crosswise of the supported saw, said means including a rockable member, a pulley provided with a series of sockets at selected radial distances from its axis, and a link having connection at one end with the rockable member and having connection at its opposite end with a selected socket.

4. A saw sharpening machine comprising a rotatable arbor, means for securing the saw to be sharpened ,rigidly upon the arbor, means connected to the arbor for rotatively advancing the arbor in successive steps, an arm projecting over and in substantially parallel relation to the plane of the saw when the latter is mounted on the arbor, said arm being pivoted for rockable movement about an axis parallel to the axis of the arbor, said arm further being transversely shiftable'along said axis, a power-driven grinder carried by the arm, means for rapidly reciprocating the arm to and fro along said axis during grinding operations, means for simultaneously rocking the arm, and means for synchronizing the rockable movement of the arm and its supported grinder in relation to the rotary movement of the arbor.

5. A machine for sharpening saws comprising an arbor for supporting the saw to be sharpened, an arm-like frame pivoted for rocking movement about an axis parallel to and spaced from the arbor, grinding means shiftably mounted on the frame for movement toward and away from the axis thereof, driving means for rotating the arbor, a cam operably connected to the frame and driven in timed relation to the driving means whereby to generatively grind a saw tooth having a predetermined contour depending upon the shape of the cam, and means for reciprocating the grinder longitudinally with respect to said axis during its tooth generating movement.

6. A machine for sharpening saws comprising an arbor for supporting the saw to be sharpened, an arm-like frame pivoted for rocking movement about an axis parallel to and spaced from the arbor, a cross-head shiftably mounted on the frame for movement toward and away from the axis thereof, a power driven rotary grinder shiftably mounted on the cross-head for movement in a direction transverse to the direction of movement of the cross-head, driving means for rotating the arbor, and a cam operably connected to the frame and driven in timed relation to the driving means whereby to generatively grind a saw tooth having a predetermined contour depending upon the shape of the cam.

CLAUD E. DRAKE. 

